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      <title>如何在Zookeeper中实现分布式锁 - 交互式测验</title>
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      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>如何在Zookeeper中实现分布式锁 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
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                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
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                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
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                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
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          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在Zookeeper分布式锁实现中，客户端尝试获取锁时会创建什么类型的节点，为什么？",
    "options": [
      "持久节点 (PERSISTENT)，因为它需要永久存在以记录锁的状态。",
      "临时节点 (EPHEMERAL)，因为它比其他节点类型创建更快。",
      "临时顺序节点 (EPHEMERAL_SEQUENTIAL)，因为它既能保证客户端下线后锁自动释放，又能为等待者提供公平的排队顺序。",
      "持久顺序节点 (PERSISTENT_SEQUENTIAL)，因为它能记录所有历史的锁请求顺序。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "正确答案是“临时顺序节点”。“临时”特性保证了当客户端会话结束（例如程序崩溃）时，节点会自动删除，从而释放锁，防止了死锁的发生。“顺序”特性则为每个尝试获取锁的客户端分配一个唯一的、递增的序号，这为实现公平的先到先得排队机制提供了基础。",
    "source": "文档中「1. 创建锁节点」部分",
    "hint": "文档提到，当客户端需要获取锁时，它会在根节点下创建一个节点，并且这种节点的特性确保了节点的顺序。"
  },
  {
    "question": "根据文档描述，一个客户端如何判断自己已经成功获得了Zookeeper分布式锁？",
    "options": [
      "当它创建的节点成为其父节点（如/locks）下序号最小的节点时。",
      "当它收到Zookeeper服务器返回的一个特殊的“锁定成功”确认码时。",
      "只要在/locks目录下成功创建了自己的节点，就意味着获得了锁。",
      "当它成功监听到前一个节点被删除的事件时。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "Zookeeper分布式锁的裁决机制是：所有请求锁的客户端都会在锁的根目录下创建自己的临时顺序节点，但只有创建的节点序号是当前所有子节点中最小的那个客户端，才被认为成功获取了锁。",
    "source": "文档中「2. 检查锁的状态」部分",
    "hint": "每个客户端在创建临时顺序节点后，需要检查在根节点下的所有节点，并判断自己创建的节点是否是当前..."
  },
  {
    "question": "如果一个客户端发现自己未能立即获得锁，它应该采取什么行动来等待锁的释放？",
    "options": [
      "对锁的根节点（/locks）设置监听，等待子节点数量发生变化。",
      "监听并等待其序号紧邻的前一个节点的删除事件。",
      "进入一个循环，定期查询/locks下的所有子节点，直到自己的节点序号变为最小。",
      "立即删除自己的节点，并在一个随机的延迟后重新尝试获取锁。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "这种“监听前一个节点”的设计是为了避免“惊群效应”。如果所有等待的客户端都监听同一个节点，那么当锁被释放时，所有客户端都会被同时唤醒，造成不必要的网络风暴和服务器压力。只监听前一个节点，可以确保每次只有一个客户端被精确唤醒。",
    "source": "文档中「2. 检查锁的状态」部分",
    "hint": "如果不是最小节点，客户端需要监听自己前一个顺序节点的...事件。"
  },
  {
    "question": "文档中提到的Zookeeper分布式锁“可靠性高”的一个关键原因是什么？",
    "options": [
      "Zookeeper集群通过选举机制解决了单点故障问题。",
      "因为锁节点是临时节点，即使持有锁的客户端崩溃，锁也能被自动释放。",
      "Zookeeper的网络通信协议非常稳定，几乎不会中断。",
      "锁的释放操作必须由客户端显式调用，确保了操作的确定性。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "这是Zookeeper分布式锁最核心的可靠性保障。在分布式系统中，单个节点的故障是常态，如果锁不能在节点故障后自动释放，就会导致资源被永久锁定，即死锁。临时节点的特性优雅地解决了这个问题。",
    "source": "文档中「3. 释放锁」和「优点」部分",
    "hint": "文档在“自动释放”和“可靠性高”两个小节中都强调了临时节点的一个重要特性。"
  },
  {
    "question": "根据文档分析，使用Zookeeper实现分布式锁存在的一个主要缺点是什么？",
    "options": [
      "实现逻辑过于简单，无法处理复杂的并发场景。",
      "锁的互斥性无法得到严格保证，可能出现多个客户端同时持有锁的情况。",
      "在客户端数量众多或锁竞争激烈时，频繁的节点操作和网络通信会带来显著的性能开销。",
      "锁的粒度只能是集群级别，无法对单个资源进行加锁。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "每一次获取锁和释放锁的操作都涉及到与Zookeeper集群的多次网络交互（创建节点、获取子节点列表、设置监听、删除节点等）。在高并发环境下，这些操作会成为系统的瓶颈，对Zookeeper服务器造成较大压力，并增加请求的延迟。",
    "source": "文档中「缺点」部分",
    "hint": "文档中提到，使用Zookeeper实现分布式锁涉及到...和节点操作，这可能会导致性能开销，特别是在高并发环境下。"
  },
  {
    "question": "在示例代码和文档描述中，用于存放所有锁节点的根节点（如 /locks）应该被创建成什么类型？",
    "options": [
      "临时节点 (EPHEMERAL)，因为它只在有客户端竞争锁时才需要存在。",
      "持久节点 (PERSISTENT)，因为它需要作为所有锁请求的稳定入口，不能随客户端会话结束而消失。",
      "容器节点 (CONTAINER)，它可以在没有子节点时自动被删除以节省资源。",
      "临时顺序节点 (EPHEMERAL_SEQUENTIAL)，与子节点保持类型一致。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "锁的根节点是整个锁机制的命名空间，它必须是持久的，以确保任何时候客户端都能在它下面创建自己的锁节点。如果根节点是临时的，那么创建它的客户端一旦下线，所有正在等待或持有锁的节点都会因为父节点被删除而失效，这将破坏整个锁机制。",
    "source": "文档中「1. 创建锁节点」和「示例代码」部分",
    "hint": "思考一下，如果这个根节点会随着创建它的第一个客户端的下线而消失，会发生什么？示例代码中的`createLockRootNodeIfNotExists`方法也明确了其创建模式。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
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        const hintContainerEl = document.getElementById('hint-container');

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          optionsListEl.innerHTML = '';
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            nextBtn.style.display = 'block';
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            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
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        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
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                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
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                    child.style.borderColor = '#f5c6cb';
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            } else {
                hintContainerEl.style.display = 'none';
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        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  